NationMaster - Encyclopedia: NEAR Shoemaker

The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker), renamed after its launch in honor of planetary scientist Eugene M. Shoemaker, is a robotic space probe designed to study the near-Earth asteroid Eros from close orbit over a period of a year. The primary scientific objective of NEAR was to return data on the bulk properties, composition, mineralogy, morphology, internal mass distribution and magnetic field of Eros. Secondary objectives include studies of regolith properties, interactions with the solar wind, possible current activity as indicated by dust or gas, and the asteroid spin state. This data will be used to help understand the characteristics of asteroids in general, their relationship to meteorites and comets, and the conditions in the early solar system. To accomplish these goals, the spacecraft was equipped with an X-ray/gamma ray spectrometer, a near-infrared imaging spectrograph, a multi-spectral camera fitted with a CCD imaging detector, a laser rangefinder, and a magnetometer. A radio science experiment was also performed using the NEAR tracking system to estimate the gravity field of the asteroid. The total mass of the instruments was 56 kg, and they required 81 W power. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links WholeEros. ... Image File history File links WholeEros. ... Eugene Shoemaker at a stereoscopic microscope used for asteroid discovery Eugene Merle Shoemaker (or Gene Shoemaker) (April 28, 1928 – July 18, 1997) was one of the founders of the fields of planetary science and is best known for co-discovering the Comet Shoemaker-Levy 9 with his wife Carolyn... An artists interpretation of the MESSENGER spacecraft at Mercury A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. ... Technicians work on the Ulysses space probe. ... Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earths orbit. ... The asteroid 433 Eros (eer-os) was named after the Greek god of love Eros. ... A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. ... This article or section is in need of attention from an expert on the subject. ... Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ... Regolith (Greek: blanket rock) is a layer of loose, heterogeneous material covering solid rock. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... 253 Mathilde, a C-type asteroid. ... It has been suggested that micrometeoroid be merged into this article or section. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... X-ray spectroscopy is a gathering name for several spectroscopic techniques for determining the electronic structure of materials by using x-ray excitation. ... Source of image data: Los Alamos National Laboratory The Gamma Ray Spectrometer (GRS) uses the gamma-ray part of the spectrum to look for the presence of 20 elements from the periodic table, and is used in the exploration of Mars. ... A charge-coupled device (CCD), is an integrated circuit containing an array of linked, or coupled, capacitors. ... A laser range-finder is a device which uses a laser beam in order to determine the distance to a reflective object. ... A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. ... This article covers the physics of gravitation. ...

Mission profile

Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ... February 17 is the 48th day of the year in the Gregorian calendar. ...

Summary

The primary goal of the mission was to study the near Earth asteroid 433 Eros from orbit for approximately one year. Eros is an S-type asteroid approximately 13 × 13 × 33 km in size, the second largest near-Earth asteroid. Initially the orbit was circular with a radius of 200 km. The radius of the orbit was brought down in stages to a 50 × 50 km orbit on 30 April 2000 and decreased to 35 × 35 km on July 14, 2000. The orbit was raised over succeeding months to a 200 × 200 km orbit and then slowly decreased and altered to a 35 × 35 km retrograde orbit on December 13, 2000. The mission ended with a touchdown in the "saddle" region of Eros on February 12, 2001. The asteroid 433 Eros (eer-os) was named after the Greek god of love Eros. ... S-type asteroids are of a silicaceous (stony) composition, hence the name. ... is the 120th day of the year (121st in leap years) in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... is the 195th day of the year (196th in leap years) in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... December 13 is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... February 12 is the 43rd day of the year in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ...

Some scientists claim that the ultimate goal of the mission was to link Eros, an asteroidal body, to meteorites recovered on Earth. With sufficient data on chemical composition, a causal link could be established between Eros and other S-type asteroids, and those meteorites believed to be pieces of S-type asteroids (perhaps Eros itself). Once this connection is established, meteorite material can be studied with large, complex, and evolving equipment, and the results extrapolated to bodies in space. NEAR-Shoemaker did not prove or disprove this link to the satisfaction of scientists. However, it is undeniable that NEAR data advanced the field of asteroidal studies tremendously.

Image File history File links Download high resolution version (2175x2186, 2419 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (2175x2186, 2419 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ...

The journey to Eros

After launch on a Delta 7925-8 (a Delta II Lite launch vehicle with nine strap-on solid-rocket boosters and a Star 48 (PAM-D) third stage) and exit from Earth orbit, NEAR entered the first part of its cruise phase. It spent most of this phase in a minimal activity "hibernation" state, which ended a few days before the flyby of the 61 km diameter asteroid 253 Mathilde on June 27, 1997. The spacecraft flew within 1200 km of Mathilde at 12:56 UT at 9.93 km/s, returning imaging and other instrument data. On July 3, 1997 NEAR executed the first major deep space maneuver, a two-part burn of the main 450 N thruster. This decreased the velocity by 279 m/s and lowered perihelion from 0.99 AU to 0.95 AU. The Earth gravity assist swingby occurred on January 23, 1998 at 7:23 UT. The closest approach was 540 km, altering the orbital inclination from 0.5 to 10.2 degrees, and the aphelion distance from 2.17 to 1.77 AU, nearly matching those of Eros. Instrumentation was active at this time. The Delta II family of launch vehicles was designed and built by Boeings Integrated Defense Systems division and has been in service since 1989. ... 253 Mathilde is a Main belt asteroid that was visited by the NEAR Shoemaker spacecraft on its way to asteroid 433 Eros. ... June 27 is the 178th day of the year (179th in leap years) in the Gregorian calendar. ... Year 1997 (MCMXCVII) was a common year starting on Wednesday (link will display full 1997 Gregorian calendar). ... is the 184th day of the year (185th in leap years) in the Gregorian calendar. ... Year 1997 (MCMXCVII) was a common year starting on Wednesday (link will display full 1997 Gregorian calendar). ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The astronomical unit (AU or au or a. ... In orbital mechanics and aerospace engineering, a gravitational slingshot or gravity assist is the use of the gravity of a planet or other celestial body to alter the path and speed of a spacecraft. ... is the 23rd day of the year in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

Failure of first attempt at orbital insertion

The first of four scheduled rendezvous burns on December 20, 1998 at 22:00 UT aborted due to a software problem. Contact was lost immediately after this and was not re-established for over 24 hours. The original mission plan called for these four burns to be followed by an orbit insertion burn on January 10, 1999, but the abort of the first burn and loss of communication made this impossible. A new plan was put into effect in which NEAR flew by Eros on December 23, 1998 at 18:41:23 UT at a speed of 965 m/s and a distance of 3827 km from the center of mass of Eros. Images of Eros were taken by the camera, data were collected by the near IR spectrograph, and radio tracking was performed during the flyby. A rendezvous maneuver was performed on January 3, 1999 involving a thruster burn to match NEAR's orbital speed to that of Eros. A hydrazine thruster burn took place on January 20 to fine-tune the trajectory. On August 12 a two minute thruster burn slowed the spacecraft velocity relative to Eros to 300 km/h. is the 354th day of the year (355th in leap years) in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... January 10 is the 10th day of the year in the Gregorian calendar. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... December 23 is the 357th day of the year (358th in leap years) in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... Look up ir in Wiktionary, the free dictionary. ... January 3 is the 3rd day of the year in the Gregorian calendar. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... Hydrazine should not be confused with Hydergine (Ergoloid mesylates) an ergot alkaloid Hydrazine is the chemical compound with formula N2H4, widely used in chemical synthesis. ... January 20 is the 20th day of the year in the Gregorian calendar. ... August 12 is the 224th day of the year (225th in leap years) in the Gregorian calendar. ...

Orbital insertion

Orbital insertion around Eros occurred on 14 February 2000 at 15:33 UT (10:33 AM EST) after NEAR completed a 13 month heliocentric orbit which closely matched the orbit of Eros. A rendezvous maneuver was completed on February 3 at 17:00 UT, slowing the spacecraft from 19.3 to 8.1 m/s relative to Eros. Another maneuver took place on February 8 increasing the relative velocity slightly to 9.9 m/s. Searches for satellites of Eros took place on January 28, and 4 and 9 February, none were found. The scans were for scientific purposes and to mitigate any chances of collision with a satellite. NEAR went into a 321 x 366 km orbit around Eros on February 14. The orbit was slowly decreased to a 35 km circular polar orbit by July 14. NEAR remained in this orbit for 10 days and then was backed out in stages to a 100 km circular orbit by September 5, 2000. Maneuvers in mid-October led to a flyby of Eros within 5.3 km of the surface at 07:00 UT on 26 October. Image File history File links NEARtrajectory. ... Image File history File links NEARtrajectory. ... Orbit insertion is a maneuver performed by an inter-planetary spacecraft designed to allow the spacecraft to be captured into orbit around a planet or other body such as a moon. ... Insert non-formatted text here{| style=float:right; |- | paul is so hot sophie loves him |- | |} is the 45th day of the year in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... February 3 is the 34th day of the year in the Gregorian Calendar. ... is the 39th day of the year in the Gregorian calendar. ... January 28 is the 28th day of the year in the Gregorian calendar. ... Insert non-formatted text here{| style=float:right; |- | paul is so hot sophie loves him |- | |} is the 45th day of the year in the Gregorian calendar. ... is the 195th day of the year (196th in leap years) in the Gregorian calendar. ... is the 248th day of the year (249th in leap years) in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... October 26 is the 299th day of the year (300th in leap years) in the Gregorian calendar. ...

Orbits and landing

Following the flyby NEAR moved to a 200 km circular orbit and shifted the orbit from prograde near-polar to a retrograde near-equatorial orbit. By December 13, 2000 the orbit was shifted back to a circular 35 km low orbit. Starting on January 24, 2001 the spacecraft began a series of close passes (5 to 6 km) to the surface and on January 28 passed 2 to 3 km from the asteroid. The spacecraft then made a slow controlled descent to the surface of Eros ending with a touchdown just to the south of the saddle-shaped feature Himeros on February 12, 2001 at approximately 20:01 UT (3:01 p.m. EST). To the surprise of the controllers, the spacecraft was undamaged and operational after the landing at an estimated speed of 1.5 to 1.8 meters per second (thus becoming the first spacecraft to soft-land on an asteroid). After receiving an extension of antenna time on the Deep Space Network, the spacecraft's gamma-ray spectrometer was reprogrammed to collect data on Eros' composition from a vantage point about four inches from the surface where it was ten times more sensitive than when it was used in orbit. [2] Image File history File links ErosFrom1150m. ... Image File history File links ErosFrom1150m. ... Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... December 13 is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... January 24 is the 24th day of the year in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... January 28 is the 28th day of the year in the Gregorian calendar. ... February 12 is the 43rd day of the year in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Deep Space Network (DSN) is an international network of radio antennas that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. ...

At 7 p.m. EST on February 28, 2001 the last data signals were received from NEAR Shoemaker before it was shut down. A final attempt to communicate with the spacecraft on December 10, 2002 was unsuccessful. [3] February 28 is the 59th day of the year in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... December 10 is the 344th day (345th in leap years) of the year in the Gregorian calendar, 21 days before the next year. ... For album titles with the same name, see 2002 (album). ...

Spacecraft and subsystems

The spacecraft has the shape of an octagonal prism, approximately 1.7 m on a side, with four fixed gallium arsenide solar panels in a windmill arrangement, a fixed 1.5 m X-band high-gain radio antenna with a magnetometer mounted on the antenna feed, and an X-ray solar monitor on one end (the forward deck), with the other instruments fixed on the opposite end (the aft deck). Most electronics are mounted on the inside of the decks. The propulsion module is contained in the interior. Image File history File links Download high resolution version (458x606, 198 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (458x606, 198 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The Delta II family of launch vehicles was designed and built by Boeings Integrated Defense Systems division and has been in service since 1989. ... This article is about the chemical compound. ... Solar Panel made by BP Solar The solar panels (photovoltaic arrays) on this small yacht at sea can charge the 12 V batteries at up to 9 Amps in full, direct sunlight. ... The X band (3-cm radar spot-band) of the microwave band of the electromagnetic spectrum roughly ranges from 5. ... A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. ...

The craft is three-axis stabilized and uses a single bipropellant (hydrazine / nitrogen tetroxide) 450 newton (N) main thruster, and four 21 N and seven 3.5 N hydrazine thrusters for propulsion, for a total delta-V potential of 1450 m/s. Attitude control is achieved using the hydrazine thrusters and four reaction wheels. The propulsion system carries 209 kg of hydrazine and 109 kg of NTO oxidizer in two oxidizer and three fuel tanks. F-1 rocket engine (The kind used by the Saturn V.) A bipropellant rocket engine is a rocket engine that uses two fluid propellants stored in separate tanks that are injected into, and undergo a strong exothermic reaction, in a rockets combustion chamber. ... Hydrazine should not be confused with Hydergine (Ergoloid mesylates) an ergot alkaloid Hydrazine is the chemical compound with formula N2H4, widely used in chemical synthesis. ... Nitrogen tetroxide (or Dinitrogen tetroxide) (N2O4) is a hypergolic propellant often used in combination with a hydrazine-based rocket fuel. ... The newton (symbol: N) is the SI unit of force. ... General In general physics delta-v is simply the change in velocity. ...

Power is provided by four 1.8 by 1.2 meter gallium arsenide solar panels which can produce 400 watts at 2.2 AU (329,000,000 km), NEAR's maximum distance from the Sun, and 1800 W at one AU (150,000,000 km). Power is stored in a nine ampere-hour, 22-cell rechargeable super nickel-cadmium battery. The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ... The astronomical unit (AU or au or a. ... The nickel-cadmium battery (commonly abbreviated NiCd or NiCad) is a popular type of rechargeable battery for portable electronics and toys. ...

Spacecraft guidance is achieved through the use of a sensor suite of five digital solar attitude detectors, an inertial measurement unit, (IMU) and a star tracker camera pointed opposite the instrument pointing direction. The IMU contains hemispherical resonator gyroscopes and accelerometers. Four reaction wheels (arranged so that any three can provide complete three-axis control) are used for normal attitude control. The thrusters are used to dump angular momentum from the reaction wheels, as well as for rapid slew and propulsive maneuvers. Attitude control is to 0.1 degree, line-of-sight pointing stability is within 50 microradians over one second, and post-processing attitude knowledge is to 50 microradians. A gyroscope For other uses, see Gyroscope (disambiguation). ... A momentum wheel is a type of flywheel used primarily by spacecraft to change their angular momentum without using fuel for rockets or other reaction devices. ... This gyroscope remains upright while spinning due to its angular momentum. ...

The command and data handling subsytem is composed of two redundant command and telemetry processors and solid state recorders, a power switching unit, and an interface to two redundant 1553 standard data buses for communications with other subsystems. The solid state recorders are constructed from 16 Mbit IBM Luna-C DRAMs. One recorder has 1.1 gigabits of storage, the other has 0.67 gigabits. International Business Machines Corporation (IBM, or colloquially, Big Blue) (NYSE: IBM) (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, New York, USA. The company manufactures and sells computer hardware, software, and services. ... Dram can mean several things: For the imperial unit of volume see dram (unit), commonly used to describe a measure of Scotch whisky For the imperial unit of weight or mass see avoirdupois and apothecaries system (of mass) For the Armenian monetary unit see dram (currency) DRAM is a type... A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ...

The NEAR mission was the first launch of NASA's Discovery Program, a series of small-scale spacecraft designed to proceed from development to flight in under three years for a cost of less than $150 million. The construction, launch, and 30 day cost for this mission is estimated at $122 million. NASAs Discovery Program is a series of lower-cost, highly focused scientific space missions. ...

References

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

Categories: NASA probes | Discovery program The Space Shuttle Discovery as seen from the International Space Station. ... 253 Mathilde, a C-type asteroid. ... Galileo is prepared for mating with the IUS booster Galileo and Inertial Upper Stage being deployed after being launched by the Space Shuttle Atlantis on the STS-34 mission Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. ... The spacecraft Deep Space 1 was launched October 24, 1998 on top of a Delta II rocket. ... An artists rendering of Stardust (NASA image) The Stardust capsule with cometary and interstellar samples landed at the U.S. Air Force Utah Test and Training Range at 10:10 UTC (15 January 2006) in the Bonneville Salt Flats. ... New Horizons on the launchpad New Horizons at its liftoff New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... Rosetta is a European Space Agency-led unmanned space mission launched in 2004 intended to study the comet 67P/Churyumov-Gerasimenko. ... For other uses, see Hayabusa (disambiguation). ... Rosetta is a European Space Agency-led unmanned space mission launched in 2004 intended to study the comet 67P/Churyumov-Gerasimenko. ... For other uses, see Hayabusa (disambiguation). ... Philae (previously known as RoLand) is the name of the lander that accompanies the Rosetta spacecraft. ... The Dawn Mission is a NASA mission that will send the Dawn spacecraft, a robotic space probe, to the asteroid belt. ...

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